U.S. patent application number 13/473966 was filed with the patent office on 2013-11-21 for wire-wrapped grooved rollers for cleaning action using brush-like system.
This patent application is currently assigned to XEROX CORPORATION. The applicant listed for this patent is Timothy P. Foley, Douglas A. Gutberlet, Frank B. Tamarez Gomez. Invention is credited to Timothy P. Foley, Douglas A. Gutberlet, Frank B. Tamarez Gomez.
Application Number | 20130308987 13/473966 |
Document ID | / |
Family ID | 49581401 |
Filed Date | 2013-11-21 |
United States Patent
Application |
20130308987 |
Kind Code |
A1 |
Tamarez Gomez; Frank B. ; et
al. |
November 21, 2013 |
WIRE-WRAPPED GROOVED ROLLERS FOR CLEANING ACTION USING BRUSH-LIKE
SYSTEM
Abstract
An apparatus for developing in a development zone a latent image
recorded on a surface, including a housing defining a chamber
storing at least a supply of toner therein; a donor member disposed
at least partially in the chamber of the housing and spaced from
the surface, the donor member being adapted to rotate about a
longitudinal axis to transport toner to the development zone in a
region opposed from the surface; and a wire assembly module mounted
in the development zone and extending in a direction transverse to
the longitudinal axis, the wire assembly module including a wire
and a drive/cleaning system for translating and cleaning portions
of the wire in the development zone, and a power supply for
electrically biasing the wire to form a toner powder cloud in the
development zone for developing the latent image.
Inventors: |
Tamarez Gomez; Frank B.;
(Rochester, NY) ; Foley; Timothy P.; (Marion,
NY) ; Gutberlet; Douglas A.; (Ontario, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tamarez Gomez; Frank B.
Foley; Timothy P.
Gutberlet; Douglas A. |
Rochester
Marion
Ontario |
NY
NY
NY |
US
US
US |
|
|
Assignee: |
XEROX CORPORATION
Norwalk
CT
|
Family ID: |
49581401 |
Appl. No.: |
13/473966 |
Filed: |
May 17, 2012 |
Current U.S.
Class: |
399/266 |
Current CPC
Class: |
G03G 2215/0643 20130101;
G03G 2215/0621 20130101; G03G 15/0803 20130101; G03G 21/00
20130101 |
Class at
Publication: |
399/266 |
International
Class: |
G03G 15/08 20060101
G03G015/08 |
Claims
1. An apparatus for developing in a development zone a latent image
recorded on a surface, including: a housing defining a chamber
storing at least a supply of toner therein; a donor member disposed
at least partially in the chamber of said housing and spaced from
the surface, said donor member being configured to rotate about a
longitudinal axis to transport toner to the development zone in a
region opposed from the surface; and a wire assembly module mounted
in the development zone and extending in a direction transverse to
the longitudinal axis, said wire assembly module including a wire
and a drive system configured to translate portions of the wire in
the development zone, and the wire module configured to
electrically bias said wire to detach toner from said donor member
so as to form a toner powder cloud in the development zone with
detached toner from the toner cloud developing the latent image,
said wire assembly module further includes a stringing system
configured to arrange said wire into a plurality of wires with
adjacent wires being spaced from and substantially parallel to one
another, the drive system including a roller configured to position
the plurality of wires within a cleaning zone, the cleaning zone
including a cleaning device fixed to the wire assembly module and
the cleaning device configured to remove toner from the plurality
of wires.
2. An apparatus according to claim 1, wherein said drive system is
configured to support said plurality of wires at a preselected
tension.
3. The apparatus according to claim 1, further comprising: a second
roller operatively associated with the first roller, the second
roller configured to position the plurality of wires within a
second cleaning zone, the second cleaning zone including a second
cleaning device fixed to the wire assembly module and the cleaning
device configured to remove toner from the plurality of wires.
4. The apparatus according to claim 1, wherein the cleaning device
is one of a brush and a scraper.
5. The apparatus according to claim 1, wherein the roller includes
grooves to position the wires within the cleaning zone.
6. The apparatus according to claim 1, further comprising: a motor
operatively connected to the roller, the motor configured to rotate
the roller.
7. The apparatus according to claim 6, further comprising: a
controller operatively connected to the motor, the controller
configured to control a rotational speed of the roller.
8. The apparatus according to claim 7, wherein the stringing system
includes one or more channel assemblies configured to arrange said
wire into a plurality of wires with adjacent wires being spaced
from and substantially parallel to one another.
9. The apparatus according to claim 8, wherein the wire assembly
module includes one or more electrical connection points
operatively connected to the plurality of elongated wires.
10. The apparatus according to claim 1, the stringing system
including one or more tensioning devices configured to adjust the
tension of translated portions of the wire in the development
zone.
11. An electrode wire assembly module operatively associated with a
development zone comprising: a plurality of wires; a stringing
system configured to arrange said wires into a plurality of
elongated wires with adjacent wires being spaced from and
substantially parallel to one another; and a drive system
configured to translate portions of the wires in the associated
development zone, and the drive system including a roller
configured to position the plurality of wires within a cleaning
zone, the cleaning zone including a cleaning device fixed to the
wire assembly module and the cleaning device configured to remove
toner from the plurality of wires, wherein the wire assembly module
is configured to electrically bias said wires to detach toner from
an associated donor member so as to form a toner powder cloud in
the associated development zone.
12. The wire assembly module according to claim 11, wherein said
drive system is configured to support said plurality of wires at a
preselected tension.
13. The wire assembly module according to claim 11, the drive
system further comprising: a second roller operatively associated
with the first roller, the second roller configured to position the
plurality of wires within a second cleaning zone, the second
cleaning zone including a second cleaning device fixed to the wire
assembly module and the cleaning device configured to remove toner
from the plurality of wires.
14. The wire assembly module according to claim 11, wherein the
cleaning device is one of a brush and a scraper.
15. The wire assembly according to claim 11, wherein the roller
includes grooves to position the wires within the cleaning
zone.
16. The wire assembly module according to claim 11, further
comprising: a motor operatively connected to the roller, the motor
configured to rotate the roller.
17. The wire assembly module according to claim 16, further
comprising: a controller operatively connected to the motor, the
controller configured to control a rotational speed of the
roller.
18. The wire assembly module according to claim 17, wherein the
stringing system includes one or more channel assemblies configured
to arrange said wire into a plurality of wires with adjacent wires
being spaced from and substantially parallel to one another.
19. The wire assembly module according to claim 18, wherein the
wire assembly module includes one or more electrical connection
points operatively connected to the plurality of elongated
wires.
20. The wire assembly module according to claim 11, the stringing
system including one or more tensioning devices configured to
adjust the tension of translated portions of the wire in the
development zone.
21. A printing system comprising: a latent image recorded on a
surface; a housing defining a chamber storing a supply of toner
therein; a donor member disposed at least partially in the chamber
of said housing and spaced from the surface, said donor member
being configured to rotate about a longitudinal axis to transport
toner to a development zone, the development zone including a
region opposed from the latent image recorded on the surface; and a
wire assembly mounted in the development zone and extending in a
direction transverse to the longitudinal axis, said wire assembly
including a wire and a drive system configured to translate
portions of the wire in the development zone, the wire assembly
configured to electrically bias the wire to detach toner from said
donor member so as to form a toner cloud developing the latent
image, the drive system including a roller configured to position
the wire within a cleaning zone, the cleaning zone including a
cleaning device configured to remove toner from the wire.
22. The printing system according to claim 21, further comprising:
a motor operatively connected to the roller, the motor configured
to rotate the roller; and a controller operatively connected to the
motor, the controller configured to control a rotational speed of
the roller.
23. The printing system according to claim 22, further comprising:
a second roller operatively associated with the first roller; and a
second motor operatively connected to the second roller, the second
motor configured to rotate the second motor, wherein the controller
is operatively connected to the first and second motors, and the
controller is configured to control the rotational speed of the
first roller and a rotational speed of the second roller.
Description
BACKGROUND
[0001] Generally, the process of electrophotographic printing
includes charging a photoconductive member to a substantially
uniform potential so as to sensitize the surface thereof. The
charged portion of the photoconductive surface is exposed to a
light image of an original document being reproduced. This records
an electrostatic latent image on the photoconductive member. After
the electrostatic latent image is recorded on the photoconductive
member, the latent image is developed by bringing a developer
material into contact therewith. Two component and single component
developer materials are commonly used. A typical two component
developer material has magnetic carrier granules with toner
particles adhering triboelectrically thereto. A single component
developer material typically comprises toner particles. Toner
particles are attracted to the latent image forming a toner powder
image on the photoconductive member. The toner powder image is
subsequently transferred to a copy sheet. Finally, the toner powder
image is heated to permanently fuse it to the copy sheet in image
configuration.
[0002] One type of single component development system is a
scavengeless development system that uses a donor roll for
transporting charged toner to a development zone. A plurality of
electrode wires are closely spaced to the donor roll in the
development zone. An AC voltage is applied to the wires forming a
toner cloud in the development zone. The electrostatic fields
generated by the latent image attract toner from the toner cloud to
develop the latent image. A hybrid scavengeless development system
employs a magnetic brush developer roller for transporting carrier
having toner adhering triboelectrically thereto. The donor roll and
magnetic brush roll are electrically biased relative to one
another. Toner is attracted to the donor roll from the magnetic
brush roll. The donor roll transports the charged toner to a
development zone. The electrically biased electrode wires detach
the toner from the donor roll forming a toner powder cloud in the
development zone, and the latent image attracts the toner particles
thereto. In this way, the latent image recorded on the
photoconductive member is developed with the toner particles. It
has been found that streaks are formed in the developed latent
image when debris is trapped in, or when toner and/or toner
constituents builds up on the electrode wires. Heretofore, the
electrode wires have been positioned substantially perpendicular to
the process direction, i.e. substantially parallel to the
longitudinal axis of the donor roll. Various types of development
systems have hereinbefore been used incorporating electrode wires
as illustrated by the following disclosures, which may be relevant
to certain aspects of the present disclosure.
[0003] U.S. Pat. No. 4,868,600 describes an apparatus wherein a
magnetic roll transports two component developers to a transfer
region where toner from the magnetic roll is transferred to a donor
roll. The donor roll transports the toner to a region opposed from
a surface on which a latent image is recorded. A pair of electrode
wires are positioned in the space between the surface and the donor
roll and are electrically biased to detach toner from the donor
roll to form a toner cloud. Detach toner from the cloud develops
the latent image.
[0004] U.S. Pat. No. 4,984,019 discloses a developer unit having a
donor roll with electrode wires disposed adjacent thereto in a
development zone. A magnetic roll transports developer material to
the donor roll. Toner particles are attracted from the magnetic
roll to the donor roll. When the developer unit is inactivated, the
electrode wires are vibrated to remove contaminants therefrom.
[0005] U.S. Pat. No. 5,422,709 teaches an apparatus in which a
donor roll advances toner to an electrostatic latent image recorded
on a photoconductive member. A plurality of electrode wires are
positioned in the space between the donor roll and the
photoconductive member. The electrode wires extend in a transverse
direction relative to the longitudinal axis of the donor roll. The
electrode wires are electrically biased to detach the toner from
the donor roll so as to form a toner cloud in the space between the
electrode wires and photoconductive members. Detached toner from
the toner cloud develops the latent image. Electrode wires contact
a portion of the surface of the donor roll. As the donor roll
rotates, friction between the electrode wires and donor roll causes
trapped debris to move away from the toner powder cloud region so
as to minimize contamination produced streaks on the developed
image.
[0006] U.S. Pat. No. 7,383,973, issued Jun. 10, 2008, by Edward A.
Enyedy and entitled WIRE MODULE FOR DEVELOPER UNIT discloses a wire
feeding mechanism for advancing a continuous length of wire along a
pathway includes a housing having two roller supports each
rotatable about a corresponding axis transverse to a wire pathway.
The roller supports are on opposite sides of the pathway and are
driveably engaged with each other. A drive roller is on each of the
roller supports for rotation therewith. The drive roller includes
an outer surface extending circumferentially about the
corresponding axis. The outer surface defines a groove having an
included angle of less than ninety degrees (90.degree.). The drive
roller on each of the roller supports compressively contacts a
continuous length of wire between the roller supports such that the
wire is advanced along the pathway in response to rotation of the
drive rollers.
[0007] U.S. Pat. No. 7,076,193, issued Jul. 11, 2006, by Wing et
al., and entitled "DRIVE ROLLERS FOR WIRE FEEDING MECHANISM"
discloses an apparatus for developing in a development zone a
latent image recorded on a surface, including a housing defining a
chamber storing at least a supply of toner therein; a donor member
disposed of at least partially in the chamber of the housing and
spaced from the surface, the donor member being adapted to rotate
about a longitudinal axis to transport toner to the development
zone in a region opposed from the surface; and a wire assembly
module mounted the development zone and extending in a direction
transverse to the longitudinal axis, the wire assembly module
including a wire and a drive system for translating portions of the
wire in the development zone, and power supply for electrically
biasing the wire to detach toner from the donor member so as to
form a toner powder cloud in the development zone with detached
toner from the toner cloud developing the latent image.
[0008] A problem with developer systems using wires is that toner
and/or toner constituents buildup on the wires over time and result
in development defects. Wire contamination is a first class of
defect in which toner and/or toner constituents build up on the
wire side that is in contact with the donor roll. Wire history is a
second class of defect in which toner and/or toner constituents
build up on the wire side away from the donor roll. Wire history
involves highly charged (though sometimes low charged) and
generally small toner or other particles being attracted to the
wire and sticking to the wire as a result of either adhesive or
electrostatic attractive forces. The result is that contaminants
build up on the electrodes, as a response to the image area
coverage history, causing visible streaks on prints. Constant
cleaning of the wires is required in order to alleviate the
above-defects, which cleaning is time-consuming and inefficient in
that it requires machine downtime.
[0009] Another problem is in machines which require large
development zones that the width of the donor roll is such that a
very large number of those wires are required to cover the whole
printable area. The wrapping of this many wires poses very serious
manufacturability challenges. In addition, the wires must all be
supported at exactly the same tension which must be maintained.
This poses both a design and manufacturability challenge, when
either a single wire or a plurality of wires is used.
[0010] The present disclosure and exemplary embodiments herein
obviates the problems noted above by providing an apparatus for
developing in a development zone a latent image recorded on a
surface, including a housing defining a chamber storing at least a
supply of toner therein; a donor member disposed of at least
partially in the chamber of said housing and spaced from the
surface, said donor member being adapted to rotate about a
longitudinal axis to transport toner to the development zone in a
region opposed from the surface; and a wire assembly module mounted
in the development zone and extending in a direction transverse to
the longitudinal axis, said wire assembly module including a wire
and a drive/cleaning system for translating portions of the wire in
the development zone and cleaning the wire, and a power supply for
electrically biasing said wire to detach toner from said donor
member so as to form a toner powder cloud in the development zone
with detached toner from the toner cloud developing the latent
image.
INCORPORATION BY REFERENCE
[0011] U.S. Pat. No. 4,868,600, by Hays et al., issued Sep. 19,
1989 and entitled "SCAVENGELESS DEVELOPMENT APPARATUS FOR USE IN
HIGHLIGHT COLOR IMAGING";
[0012] U.S. Pat. No. 4,984,019, by Folkins, issued Jan. 8, 1991 and
entitled "ELECTRODE WIRE CLEANING";
[0013] U.S. Pat. No. 5,270,483, by Inoue et al., issued Dec. 14,
1993 and entitled "DEVELOPING APPARATUS";
[0014] U.S. Pat. No. 5,321,474, by Bares, issued Jun. 14, 1994 and
entitled "ACTIVE DAMPING OF ELECTRODE WIRE VIBRATION IN
SCAVENGELESS DEVELOPMENT IN A XEROGRAPHIC APPARATUS";
[0015] U.S. Pat. No. 5,338,893, by Edmunds et al., issued Aug. 16,
1994 and entitled "DONOR ROLL WITH ELECTRODE SPACER FOR
SCAVENGELESS DEVELOPMENT IN A XEROGRAPHIC APPARATUS"
[0016] U.S. Pat. No. 5,422,709, BY Minagawa et al., issued Jun. 6,
1995 and entitled "ELECTRODE WIRE GRID FOR DEVELOPER UNIT";
[0017] U.S. Pat. No. 5,600,416, by Hart, issued Feb. 4, 1997 and
entitled "ELECTRODE WIRE TENSIONING FOR SCAVENGELESS
DEVELOPMENT";
[0018] U.S. Pat. No. 5,640,657, by Hart et al., issued Jun. 17,
1997 and entitled "ELECTRODE WIRE TWISTED LOOP MOUNTING FOR
SCAVENGELESS DEVELOPMENT";
[0019] U.S. Pat. No. 5,666,619, by Hart et al., issued Sep. 9, 1997
and entitled "ELECTRODE WIRE SUPPORT FOR SCAVENGELESS
DEVELOPMENT";
[0020] U.S. Pat. No. 6,181,896, by Zirilli et al., issued Jan. 30,
2001 and entitled "DEVELOPMENT HOUSING HAVING IMPROVED TONER
EMISSION CONTROL";
[0021] U.S. Pat. No. 7,076,193, by Wing et al., issued Jul. 11,
2006, and entitled "WIRE MODULE FOR DEVELOPER UNIT";
[0022] U.S. Pat. No. 7,383,973, by Enyedy, issued Jun. 10, 2008,
and entitled "DRIVE ROLLERS FOR WIRE FEEDING MECHANISM";
[0023] JP Patent Publication No. 04-299193, Assigned to Xerox
Corp., published Oct. 22, 1992 and entitled "STITCHER WIRE DISPLAY
UNIT";
[0024] JP Patent Publication No. 06-067547, assigned to Fuji Xerox
Co. Ltd., published Mar. 11, 1994 and entitled "DEVELOPING DEVICE";
and
[0025] JP Patent Publication No. 08-142388, assigned to Brother
Ind. Ltd., published Jun. 4, 1996 and entitled "IMAGE FORMING
APPARATUS"; are all incorporated herein by reference in their
entirety.
BRIEF DESCRIPTION
[0026] In one embodiment of this disclosure, described is an
apparatus for developing in a development zone a latent image
recorded on a surface, including a housing defining a chamber
storing at least a supply of toner therein; a donor member disposed
at least partially in the chamber of said housing and spaced from
the surface, said donor member being configured to rotate about a
longitudinal axis to transport toner to the development zone in a
region opposed from the surface; and a wire assembly module mounted
in the development zone and extending in a direction transverse to
the longitudinal axis, said wire assembly module including a wire
and a drive system configured to translate portions of the wire in
the development zone, and the wire module configured to
electrically bias said wire to detach toner from said donor member
so as to form a toner powder cloud in the development zone with
detached toner from the toner cloud developing the latent image,
said wire assembly module further includes a stringing system
configured to arrange said wire into a plurality of wires with
adjacent wires being spaced from and substantially parallel to one
another, the drive system including a roller configured to position
the plurality of wires within a cleaning zone, the cleaning zone
including a cleaning device fixed to the wire assembly module and
the cleaning device configured to remove toner from the plurality
of wires.
[0027] In another embodiment of this disclosure, described is an
electrode wire assembly module operatively associated with a
development zone comprising a plurality of wires; a stringing
system configured to arrange said wires into a plurality of
elongated wires with adjacent wires being spaced from and
substantially parallel to one another; and a drive system
configured to translate portions of the wires in the associated
development zone, and the drive system including a roller
configured to position the plurality of wires within a cleaning
zone, the cleaning zone including a cleaning device fixed to the
wire assembly module and the cleaning device configured to remove
toner from the plurality of wires, wherein the wire assembly module
is configured to electrically bias said wires to detach toner from
an associated donor member so as to form a toner powder cloud in
the associated development zone.
[0028] In still another embodiment of this disclosure, described is
a printing system comprising a latent image recorded on a surface;
a housing defining a chamber storing a supply of toner therein; a
donor member disposed at least partially in the chamber of said
housing and spaced from the surface, said donor member being
configured to rotate about a longitudinal axis to transport toner
to a development zone, the development zone including a region
opposed from the latent image recorded on the surface; and a wire
assembly mounted in the development zone and extending in a
direction transverse to the longitudinal axis, said wire assembly
including a wire and a drive system configured to translate
portions of the wire in the development zone, the wire assembly
configured to electrically bias the wire to detach toner from said
donor member so as to form a toner cloud developing the latent
image, the drive system including a roller configured to position
the wire within a cleaning zone, the cleaning zone including a
cleaning device configured to remove toner from the wire.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 illustrates a wire module including two electrode
wires according to an exemplary embodiment of this disclosure.
[0030] FIG. 2 is a detailed view of a wire module including an
electrode brush according to an exemplary embodiment of this
disclosure.
[0031] FIG. 3 is another detailed view of the wire module
illustrated in FIG. 2, the view including enlarged views of the
electrode wire grooves and channels, as well as the brush and
electrode carrier.
[0032] FIG. 4 is another detailed view of the wire module
illustrated in FIGS. 2 and 3, including enlarged views of the
electrode carrier and brush mid sections.
[0033] FIG. 5 is a schematic elevational view of an illustrative
electrophotographic printing machine.
[0034] FIG. 6 is a schematic elevational view showing the
development apparatus used in the FIG. 5 printing machine.
[0035] FIG. 7 is a view of a contaminated electrode wire associated
with a developer module used in a xerographic process.
DETAILED DESCRIPTION
[0036] As briefly discussed above, wire pollution is a major
contributor to streaks on prints. Actions by customers and service
personnel to obviate or mitigate streaks increases costs, i.e. wire
module and developer replacement, ATP and PWR toner, and decrease
productivity, i.e. ATP and service time. One problem is that
particles of toners attach to the wire module by static current
and/or friction melting.
[0037] According to one aspect of this disclosure, provided is the
use of two isolated groove rollers and cleaning brushes to remove
attached toners, i.e. wire pollution, from the electrode wires.
These rollers are rotated at a constant rpm to maintain the
electrode wire displacement from one roller to the other, while the
wire electrodes are cleaned by brushes. A voltage can be applied to
the wire through a roller and isolated from the other roller. The
rollers can dynamically rotate using a motor, pulleys or the gear
assemblies.
[0038] To avoid image quality defects after several thousand
impressions, present developer housings associated with printing
systems require extensive cleaning cycles and even replacement of
the wire module. As shown in FIG. 7, the wire becomes polluted
affecting the toner developer on a photoreceptor belt. The wire
module has high voltage cables that attract the toner from the
donor roll creating a cloud that the photoreceptor belt then
attracts. Due to the charge remaining in the electrode wire,
material sticks to the electrode wire.
[0039] Ideally, it is desirable to clean the electrode wire
continuously to prevent image quality defects. However, cleaning
cycles currently in use do not completely clean the wire and in
some cases contribute to quality defects. For example, one method
of cleaning the electrode wire is to rub the donor roll on the
electrode wire, which increases the temperature of the toner due to
friction and melts toner on the wire.
[0040] As shown in FIG. 2, this disclosure provides the use of
grooved rollers to maneuver the wire from inboard (IB) to the
outboard (OB) using mechanical parts, for example a motor, gears,
pulley, etc. The driver can be on both rollers or only one roller
and functions based on a pulling and pushing effect.
[0041] At the outboard location, as shown in FIG. 3, the wire
enters the roller grooves using wire module channels. Then, to
increase the pulling tension the wire is wrapped around the roller
and re-tensioned using the wire module channel. At the inboard
location, this procedure inverted. The input channel is at the
bottom and the re-tensioning is at the top to secure the proper
tension amount.
[0042] As the wire is advanced through the rollers groove, the wire
is cleaned by a cleaning device, such as a brushing-type system
polishing the wire per every turn of the roller, thereby ensuring
that the toner particles attached to the wire are removed.
[0043] Inasmuch as the art of electrophotographic printing is well
known, the various processing stations employed in the FIG. 5
printing machine will be shown hereinafter schematically and their
operation described briefly with reference thereto.
[0044] Referring now to the drawings, there is shown a single pass
multi-color printing machine in FIG. 5. This printing machine
employs the following components: a photoconductive belt 10,
supported by a plurality of rollers or bars 12. Photoconductive
belt 10 is arranged in a vertical orientation. Photoconductive belt
10 advances in the direction of arrow 14 to move successive
portions of the external surface of photoconductive belt 10
sequentially beneath the various processing stations disposed about
the path of movement thereof. The photoconductive belt 10 has a
major axis 120 and a minor axis 118. The major and minor axes 120,
118 are perpendicular to one another. Photoconductive belt 10 is
elliptically shaped. The major axis 120 is substantially parallel
to the gravitational vector and arranged in a substantially
vertical orientation. The minor axis 118 is substantially
perpendicular to the gravitational vector and arranged in a
substantially horizontal direction. The printing machine
architecture includes five image recording stations indicated
generally by the reference numerals 16, 18, 20, 22, and 24,
respectively. Initially, photoconductive belt 10 passes through
image recording station 16. Image recording station 16 includes a
charging device and an exposure device. The charging device
includes a corona generator 26 that charges the exterior surface of
photoconductive belt 10 to a relatively high, substantially uniform
potential. After the exterior surface of photoconductive belt 10 is
charged, the charged portion thereof advances to the exposure
device. The exposure device includes a raster output scanner (ROS)
28, which illuminates the charged portion of the exterior surface
of photoconductive belt 10 to record a first electrostatic latent
image thereon. Alternatively, a light emitting diode (LED) may be
used.
[0045] This first electrostatic latent image is developed by
developer unit 30. Developer unit 30 deposits toner particles of a
selected color on the first electrostatic latent image. After the
highlight toner image has been developed on the exterior surface of
photoconductive belt 10, photoconductive belt 10 continues to
advance in the direction of arrow 14 to image recording station
18.
[0046] Image recording station 18 includes a recharging device and
an exposure device. The charging device includes a corona generator
32 which recharges the exterior surface of photoconductive belt 10
to a relatively high, substantially uniform potential. The exposure
device includes a ROS 34 which illuminates the charged portion of
the exterior surface of photoconductive belt 10 selectively to
record a second electrostatic latent image thereon. This second
electrostatic latent image corresponds to the regions to be
developed with magenta toner particles. This second electrostatic
latent image is now advanced to the next successive developer unit
36.
[0047] Developer unit 36 deposits magenta toner particles on the
electrostatic latent image. In this way, a magenta toner powder
image is formed on the exterior surface of photoconductive belt 10.
After the magenta toner powder image has been developed on the
exterior surface of photoconductive belt 10, photoconductive belt
10 continues to advance in the direction of arrow 14 to image
recording station 20.
[0048] Image recording station 20 includes a charging device and an
exposure device. The charging device includes corona generator 38,
which recharges the photoconductive surface to a relatively high,
substantially uniform potential. The exposure device includes ROS
40 which illuminates the charged portion of the exterior surface of
photoconductive belt 10 to selectively dissipate the charge thereon
to record a third electrostatic latent image corresponding to the
regions to be developed with yellow toner particles. This third
electrostatic latent image is now advanced to the next successive
developer unit 42.
[0049] Developer unit 42 deposits yellow toner particles on the
exterior surface of photoconductive belt 10 to form a yellow toner
powder image thereon. After the third electrostatic latent image
has been developed with yellow toner, photoconductive belt 10
advances in the direction of arrow 14 to the next image recording
station 22.
[0050] Image recording station 22 includes a charging device and an
exposure device. The charging device includes a corona generator
44, which charges the exterior surface of photoconductive belt 10
to a relatively high, substantially uniform potential. The exposure
device includes ROS 46, which illuminates the charged portion of
the exterior surface of photoconductive belt 10 to selectively
dissipate the charge on the exterior surface of photoconductive
belt 10 to record a fourth electrostatic latent image for
development with cyan toner particles. After the fourth
electrostatic latent image is recorded on the exterior surface of
photoconductive belt 10, photoconductive belt 10 advances this
electrostatic latent image to the cyan developer unit 48.
[0051] Developer unit 48 deposits cyan toner particles on the
fourth electrostatic latent image. These toner particles may be
partially in superimposed registration with the previously formed
yellow powder image. After the cyan toner powder image is formed on
the exterior surface of photoconductive belt 10, photoconductive
belt 10 advances to the next image recording station 24.
[0052] Image recording station 24 includes a charging device and an
exposure device. The charging device includes corona generator 50
which charges the exterior surface of photoconductive belt 10 to a
relatively high, substantially uniform potential. The exposure
device includes ROS 52, which illuminates the charged portion of
the exterior surface of photoconductive belt 10 to selectively
discharge those portions of the charged exterior surface of
photoconductive belt 10 which are to be developed with black toner
particles. The fifth electrostatic latent image, to be developed
with black toner particles, is advanced to black developer unit
54.
[0053] At black developer unit 54, black toner particles are
deposited on the exterior surface of photoconductive belt 10. These
black toner particles form a black toner powder image which may be
partially or totally in superimposed registration with the
previously formed highlight color, yellow, magenta, and cyan toner
powder images. In this way, a multi-color toner powder image is
formed on the exterior surface of photoconductive belt 10.
Thereafter, photoconductive belt 10 advances the multi-color toner
powder image to a transfer station, indicated generally by the
reference numeral 56.
[0054] At transfer station 56, a receiving medium, i.e., paper, is
advanced from stack 58 by sheet feeders and guided to transfer
station 56. At transfer station 56, a corona generating device 60
sprays ions onto the backside of the paper. This attracts the
developed multi-color toner image from the exterior surface of
photoconductive belt 10 to the sheet of paper. Stripping assist
roller 66 contacts the interior surface of photoconductive belt 10
and provides a sufficiently sharp bend thereat so that the beam
strength of the advancing paper is stripped from photoconductive
belt 10. A vacuum transport moves the sheet of paper in the
direction of arrow 62 to fusing station 64.
[0055] Fusing station 64 includes a heated fuser roller 70 and a
back-up roller 68. The back-up roller 68 is resiliently urged into
engagement with the fuser roller 70 to form a nip through which the
sheet of paper passes. In the fusing operation, the toner particles
coalesce with one another and bond to the sheet in image
configuration, forming a multi-color image thereon. After fusing,
the finished sheet is discharged to a finishing station where the
sheets are compiled and formed into sets which may be bound to one
another. These sets are then advanced to a catch tray for
subsequent removal therefrom by the printing machine operator.
[0056] One skilled in the art will appreciate that while the
multi-color developed image has been disclosed as being transferred
to paper, it may be transferred to an intermediate member, such as
a belt or drum, and then subsequently transferred and fused to the
paper. Furthermore, while toner powder images and toner particles
have been disclosed herein, one skilled in the art will appreciate
that a liquid developer material employing toner particles in a
liquid carrier may also be used.
[0057] Invariably, after the multi-color toner powder image has
been transferred to the sheet of paper, residual toner particles
remain adhering to the exterior surface of photoconductive belt 10.
The photoconductive belt 10 moves over isolation roller 78 which
isolates the cleaning operation at cleaning station 72. At cleaning
station 72, the residual toner particles are removed from
photoconductive belt 10. Photoconductive belt 10 then moves under
spots blade 80 to also remove toner particles therefrom.
[0058] Environmental conditioning unit maintains the printing
machine components enclosed in enclosure at a predefined
temperature and humidity. The Environmental Unit (EU) is an air
conditioning unit with dual air flow discharge to provide cooling,
heating and dehumidification to the xerographic enclosure/developer
housings of the print engine. The EU provides the Print Engine
precise control of temperature and humidity to assure stability of
the PE advanced technologies so as to produce a new industry
benchmark in image quality and productivity.
[0059] Referring now to FIG. 6, there is shown the details of a
development apparatus 132 according to an exemplary embodiment of
this disclosure. The apparatus comprises a reservoir or developing
housing 164 containing developer material. The developer material
is of the two component type, that is, it comprises carrier
granules and toner particles. The reservoir 164 includes augers
168, which are rotatably-mounted in the reservoir chamber. The
augers 168 serve to transport and to agitate the developer material
within the reservoir 164 and encourage the toner particles to
adhere triboelectrically to the carrier granules. A magnetic brush
roll 170 transports developer material from the reservoir 164 to
loading nips of donor rolls 176, 178. Magnetic brush rolls are well
known, so the construction of magnetic brush roll 170 need not be
described in great detail. Briefly the magnetic brush roll 170
comprises a rotatable tubular housing within which is located a
stationary magnetic cylinder having a plurality of magnetic poles
impressed around its surface. The carrier granules of the developer
material are permeable, as the tubular housing of the magnetic
brush roll 170 rotates, the granules (with toner particles adhering
triboelectrically thereto) are attracted to the magnetic brush roll
170 and are conveyed to the donor roll loading nips. A trim bar 180
removes excess developer material from the magnetic brush roll 170
and ensures an even depth of coverage with developer material
before arrival at the loading nip of donor roll 176. At each of the
donor roll loading nips, toner particles are transferred from the
magnetic brush roll 170 to the respective donor rolls 176, 178.
[0060] Donor rolls 176, 178 transport the toner to a respective
development zone through which the photoconductive belt 10 passes.
Transfer of toner from the magnetic brush roll 170 to the donor
rolls 176, 178 can be encouraged by, for example, the application
of a suitable D.C. electrical bias to the magnetic brush roll 170
and/or donor rolls 176, 178. The D.C. bias (for example,
approximately 100 v applied to the magnetic brush roll 170)
establishes an electrostatic field between the magnetic brush roll
170 and donor rolls 176,178, which causes toner particles to be
attracted to the donor rolls 176, 178 from the carrier granules on
the magnetic brush roll 170.
[0061] The carrier granules and any toner particles that remain on
the magnetic brush roll 170 are returned to the reservoir 164 as
the magnetic brush roll 170 continues to rotate. The relative
amounts of toner transferred from the magnetic brush roll 170 to
the donor rolls 176, 178 can be adjusted, for example by: applying
different bias voltages to the donor rolls 176, 178; adjusting the
magnetic brush roll to donor roll spacing; adjusting the strength
and shape of the magnetic field at the loading nips and/or
adjusting the speeds of the donor rolls 176, 178.
[0062] At each of the development zones, toner is transferred from
the respective donor rolls 176, 178 to the latent image on the
photoconductive belt 10 to form a toner powder image on the latter.
In FIG. 6, each of the development zones is shown as having the
form, i.e. electrode wires, 186, 188 disposed in the space between
each donor rolls 176, 178 and photoconductive belt 10. FIG. 6
shows, for each donor rolls 176, 178 a respective pair of electrode
wires 186, 188 extending in a direction substantially parallel to
the longitudinal axis of the donor rolls 176, 178. The electrode
wires 186, 188 are made from thin (i.e. 50 to 100 mu. diameter)
tungsten wires which are closely spaced from the respective donor
rolls 176, 178. The distance between each pair of electrode wires
186, 188 and the respective donor rolls 176, 178 is within the
range from about 10.mu. to about 40 mu. (typically approximately 25
mu.) or the thickness of the toner layer on the donor rolls 176,
178. The electrode wires 186, 188 are self-spaced from the donor
rolls 176, 178 by the thickness of the toner on the donor rolls
176, 178. To this end the extremities of the electrode wires 186,
188 are supported by a wire module disclosed herein. The electrode
wires 186, 188 extremities are supported by a wire module so that
they are slightly below a tangent to the surface, including the
toner layer, of the donor rolls 176, 178. An alternating electrical
bias is applied to the electrode wires 186, 188 by an AC voltage
source.
[0063] The applied AC establishes an alternating electrostatic
field between each pair of electrode wires 186, 188 and the
respective donor rolls 176, 178, which is effective in detaching
toner from the surface of the donor rolls 176, 178 and forming a
toner cloud about the electrode wires 186, 188, the height of the
cloud being such as not to be substantially in contact with the
photoconductive belt 10. The magnitude of the AC voltage is
relatively low, for example in the order of 200 to 500 volts peak a
frequency ranging from about 3 kHz to about 10 kHz. A DC bias
supply (not shown) applied to donor rolls 176, 178 establishes
electrostatic fields between the photoconductive belt 10 and donor
rolls 176, 178 for attracting the detached toner particles from the
clouds surrounding the electrode wires 186, 188 to the latent image
recorded on the photoconductive surface of the photoconductive belt
10. At a spacing ranging from about 10 mu. to about 40 mu. between
the electrode wires 186, 188 and donor rolls 176, 178, an applied
voltage of 200 to 500 volts produces a relatively large
electrostatic field without risk of air breakdown.
[0064] After development, toner may be stripped from the donor
rolls 176, 178 by respective cleaning blades (not shown) so that
magnetic brush roll 170 meters fresh toner to clean donor rolls
176, 178. As successive electrostatic latent images are developed,
the toner particles within the developer material are depleted. A
toner dispenser (not shown) stores a supply of toner particles. The
toner dispenser is in communication with reservoir 164 and, as the
concentration of toner particles in the developer material is
decreased, fresh toner particles are furnished to the developer
material in the reservoir 164. The augers 168 in the reservoir
chamber mix the fresh toner particles with the remaining developer
material so that the resultant developer material therein is
substantially uniform with the concentration of toner particles
being optimized. In this way, a substantially constant amount of
toner particles is in the reservoir 164 with the toner particles
having a constant charge.
[0065] In the arrangement shown in FIG. 6, the donor rolls 176, 178
and the magnetic brush roll 170 can be rotated either "with" or
"against" the direction of motion of the photoconductive belt 10.
The developer housing employs a system to control toner emission
which is composed of two manifolds 201 and 202. The location of the
two manifolds are placed above and below the upper and lower donor
rolls respectively. The manifolds are mounted in a position to
improve emissions control as well as reductions in the flow needed
to accomplish the task.
[0066] It is believed that the foregoing description is sufficient
for purposes of the present application to illustrate the general
operation of an electrophotographic printing machine incorporating
the developer unit of the present invention therein.
[0067] It is, therefore, apparent that there has been provided in
accordance with the present invention a development system that
fully satisfies the aims and advantages hereinbefore set forth.
While this invention has been described in conjunction with a
specific embodiment thereof, it is evident that many alternatives,
modifications and variations will be apparent to those skilled in
the art. Accordingly, it is intended to embrace all such
alternatives, modifications and variations that fall within the
spirit and broad scope of the appended claims.
[0068] It will be appreciated that variants of the above-disclosed
and other features and functions, or alternatives thereof, may be
combined into many other different systems or applications. Various
presently unforeseen or unanticipated alternatives, modifications,
variations or improvements therein may be subsequently made by
those skilled in the art which are also intended to be encompassed
by the following claims.
* * * * *